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Featuring Demian Dressler, DVM and Susan Ettinger, DVM, Dip. ACVIM (Oncology), authors of The Dog Cancer Survival Guide

Spay/neuter and the association with cancer in dogs: part three

Updated: May 13th, 2019


Spay Neuter Golden Retriever: Early spay and neuter have several profound long-term effects for one of our favorite breeds.

“Reproduction is a risky affair.”

“Reproduction is a risky affair” is the attention-getting opening line in one of the studies I’ll review today (Hoffman, 2013).

But before we go through the new studies, let’s review my previous articles on this topic. They have been generating some controversy, and with good reason — this is a touchy, political subject!

In my first article, we discussed that sex hormones can promote some cancers (mammary and perianal adenomas), and that early spay/neuter surgeries effectively remove the sex hormones, and therefore can help prevent these cancers. We also talked about why a spay should be considered at time of mammary tumor removal, as dogs that are spayed within 2 years of the mammary tumor development had a survival advantage. Finally, we revealed the results of a recent systematic review of the published work on neutering and mammary tumors, which revealed the actual evidence that neutering reduces the risk of mammary tumors to be weak.

In my second article, I explored the idea that sex hormones may be PROTECTIVE again certain cancers, including very aggressive cancers such as osteosarcoma, bladder transitional cell carcinoma, prostate cancer, lymphoma, and heart tumors.

Of course, there are many factors that can influence cancer development in the body, as Dr. Dressler and I make very clear in our book The Dog Cancer Survival Guide. The reason I’m going into such detail in this series about the effects sex hormones do (and don’t) have on cancer development is because it’s important to understand each factor fully. There are some things we, as dog lovers, cannot control, and there are others that we can. It’s important to be fully informed as we fight the number one killer of dogs: cancer.

So let’s look at the latest study, one I’ve mentioned but haven’t yet fully discussed: the 2013 publication by Torres de la Riva et al called Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers.

The Effects of Neutering Goldens on Cancer and Hip Dysplasia

The Torres de la Riva study looked at veterinary hospital records and reviewed those of 759 Golden Retrievers to see what health conditions are associated with spay/neuter surgeries.

Patients were classified as intact, neutered early (< 12 months old) or neutered late (>12 months old). Let’s look at the results:

  • Hip dysplasia (HD)
    • Of early-neutered males, 10% were diagnosed with HD
    • This was two times (2X) the occurrence than intact males
  • Cranial cruciate ligament tear (CCL)
    • NO cases of CCL in intact males or intact females
    • 5% early-neutered males
    • 8% early-neutered females
  • Lymphoma (LSA)
    • Almost 10 % of early- neutered males diagnosed with LSA
      • This is three times (3X) more than intact males
    • No LSA cases in late-neutered males
    • No effect in females
  • Mast cell tumor (MCT)
    • No cases of MCT in intact females
    • 6% late-neutered females
    • No effect in males
  • Hemangiosarcoma (HSA)
    • 8 % late-neutered females
    • Four times (4X) times more than intact females and early-neutered females
    • No effect in males

According to this study, spay and neutering is associated with disease development in Golden Retrievers. Here’s a quote:

“For all five diseases analyzed in the present study, the disease rates in males and/or females were significantly increased when neutering was performed early and/or late. When a disease occurred in intact dogs, the occurrence was typically one-fourth to one-half that of early- and/or late-neutered dogs. When no intact dogs were diagnosed with a disease, such as with CCL in both sexes and MCT in females, the occurrence in early- and/or late-neutered dogs ranged between 4 and 8 percent of the sample.”

Read more about all the things that put our dogs at risk in the book. 🙁

While it is tempting to apply the results of this study to other breeds, this study was based on one breed from a single hospital database (UC Davis). We do not know if the effects of spay/neutering will be true for other breeds or all dogs. Perhaps different cancers and different joint diseases will be affected in other breeds or dogs. But since Goldens are one of the most popular American breeds and a common service dog, this is still important info even if it applies only to Goldens. (I see a lot of Golden in my Oncology Service at work.)

Still, to me, as a veterinary oncologist, this study highlights that we have much to learn about how spay/neuter affects cancer in dogs. The decision to spay or neuter and the timing of that surgery is much more complicated than we’ve thought it was.

This is especially enlightening when we realize that these surgeries are far less common in European countries than they are here. As Dr. Dressler and I remind ourselves and our clients in our book, there is more than one way to practice medicine.

I think it’s time to start having more discussions about spaying and neutering than we currently do. Especially when I look at the details provided by a second study that came out this year, titled Reproductive Capability Is Associated with Lifespan and Cause of Death in Companion Dogs (Hoffman, 2013). This study out if the University of Georgia and looked at a whopping 40,139 case from the Veterinary Medical Database (VMDB), and it reveals even more complications!

Spay/Neuter Affects How Long Dogs Live

In the Hoffman study, it was revealed that sterilization (spay/neuter) significantly affected survival of the 40,139 cases under review.

The average age of death was 7.9 years if intact, and 9.4 years if neutered.

So here it looks like sterilized dogs had an increased life expectancy (males 13.8%, females 26.3%).

Sterilized dogs were LESS likely to die of infectious disease and trauma, vascular disease, and degenerative disease.

BUT sterilized dogs were MORE likely to die of cancer and immune-mediated disease.

Why are sterilized dogs LESS likely to die of infectious disease? One thought is that the female sex hormones progesterone and estrogen can be immunosuppressive (they can suppress the immune system). Does avoiding infection lead to longer lifespans?

Sterilization increased the risk of death due to cancer, but did not increase risk for all specific kinds of cancer.

In this study, spayed females were unlikely to develop mammary cancer.  But there was an increased risk to develop transitional cell carcinoma, osteosarcoma, lymphoma, and mast cell tumors. There was no effect for squamous cell carcinoma, melanoma, and prostate cancer.

Unlike the Davis study, this study did not look at age of spay/neuter. In addition, all these cases were ones referred to teaching hospitals, which may not be representative of the general dog population. This is highlighted by the shorter overall lifespan in these dogs than seen private practice.

Does socioeconomic status come into play? Owners that cannot afford spay/neuter may also lack resources to provide medical care for disease later in life. So are dogs owned by people who can afford to spay/netuer associated with better medical care, so they appear to live longer?

We now have new evidence that demonstrates that dogs who are spayed/neutered are at increased risk of dying of some cancers. And we see that at least in Goldens, the cancer rates in males and/or females were significantly increased when neutering was performed early and/or late.  We must continue to examine when dogs are dying and WHY.

Unlike in Europe, most dogs in the United States are spayed/neutered before one year of age, and often without much discussion on the part of the veterinarian and the dog owner. It is time to start having more discussions about the very real pros and cons of spay and neuter, and the timing of these surgeries.

Live longer, live well,

Dr Sue

Other Articles in This Series

Spay/neuter and the association with cancer in dogs: part one

Spay/neuter and the association with cancer in dogs: part two

Discover the Full Spectrum Approach to Dog Cancer

Leave a Comment

  1. George Lager on May 14, 2019 at 9:51 pm

    Dr. Ettinger,

    Enjoyed your articles. I also think that this is an important topic which is never discussed in detail with our veterinarians. We only hear about the negative effects of not neutering or spaying our companion dogs.

    Has there ever been a large scale study of service dogs in general? This would be an interesting study. Most of these dogs have not been neutered because presumably it affects their performance. We decided not to neuter our 3-year old German Shepherd based on the type of evidence presented in your articles. If you are a responsible dog owner we feel that neutering is unnecessary. We have owned German Shepherds for 30 years and neutering has never suppressed aggressive behavior. In most cases, this is a matter of training.


  2. RacheliC on May 14, 2019 at 5:29 am

    Thank you so much for discussing this topic, as I know it’s a pretty controversial one. I’ve tried looking up cancer rates for dogs in Europe as I know spay/neuter is less common in some countries there, but couldn’t find that info. It would interesting to see, although there’s likely other factors coming into play.
    Do you have an opinion on spay/neuter techniques that don’t totally remove all the sex organs?

  3. Emily on March 31, 2019 at 6:08 am

    We waited until our lab/border collie was about 18 months (had to guess dob) to get him neutered. We knew letting him finish growing would decrease his risk of bone cancer. Unfortunately within days of being neutered his previously mild and manageable GI problems became so much worse. Now he’s about three weeks from his 2nd birthday and we have a diagnosis of alimentary lymphoma. I worry that had we left him intact or tried to sterilize without removing the sex organs his problems wouldn’t have gotten so much worse. I had even considered waiting until he was two to do the neuter but decided to go ahead as he was having some dominance behavior that made socializing him harder than before his big boy hormones kicked in. Then again maybe the lymphoma was just finally getting a firm hold inside him. We’re so worried considering the aggressiveness of this cancer and his young age. We want to try to give him as much time as we can without making him miserable. I will say that we love our vet and she was wonderful when our 10.5 year old cat was diagnosed with osteosarcoma in his jaw. She helped us make him as comfortable as possible until he was ready to go. She has spent hours of her own time looking for more manageable treatment options for chemo for our pup and I trust her to help us make the right calls with our baby. This is our first dog as adults and only our second time dealing with pet cancer. I think we made the right calls in having him neutered when we did but can’t help but second guess myself. Do young dogs recover well from lymphoma if remission is achieved or is his age indicative that we’re fighting a losing battle?

    • Dog Cancer Vet Team on April 1, 2019 at 8:43 am

      Hello Emily,

      Thanks for writing, and we’re sorry to hear about your boy 🙁

      As we’re not veterinarians here in customer support, we can’t offer you medical advice. However, we can provide you with information based off Dr. D’s writings 🙂

      We ALL go through a stage where we wonder if we did the right thing, and if we could have done something else. The questions you are looking to answer are never going to be answered, because none of us have a crystal ball that can see what never was.

      There are a few things that you need to take into consideration. First being, life expectancy, gained life expectancy, and median survival time. This is a really great video on what each of these mean: https://www.dogcancerblog.com/videos/life-expectancy-vs-gained-life-expectancy-in-dog-cancer-treatments/ and you may find these articles on life expectancy to be helpful!

      Dr. Sue, an oncologist who co-authored the Dog Cancer Survival Guide, dedicated an entire chapter to Lymphoma–this chapter is a must read as she writes about diagnosis, prognosis, treatments, protocols, relapses, and more. She also wrote this article on What I Would Do For My Dog with Lymphoma, that you may also find helpful.

      You also have to factor in your guardian type. Do you want your boy to be as comfortable as possible? Are you okay with handling the side effects of particular treatments? How important is quality of life? Do you think he would be the same after chemo? These are just some of the questions that you have to answer when determining a treatment plan!

      Here’s a link to an article on guardian types that you may find helpful: https://www.dogcancerblog.com/blog/why-your-personality-is-so-important-to-your-dog-with-cancer/

      We can’t tell you what the right choice is because we’re not vets, each dog and their situation is different, and we don’t know your boy. But you do. And once you figure out what is most important to you both, you can then make a more informed decision 🙂

      We hope this helps! 🙂

  4. Pam Johnson on February 1, 2018 at 7:22 pm

    I find your articles very interesting because I had a Tibetan Spaniel, neutered at 5 years of age, that had a rare Cutaneous Lymphoma at the age of 14. Now, I’m wondering if it’s because we had him neutered.
    Also, my female Tibbie was spayed at 2 years of age after having some puppies but lived a pretty healthy life till 15 when she developed cataracts and dementia. Both were fed the same diet and raised in the same environment. She never developed mammary tumors or have any kind of cancer. Just age related diseases.
    I find it fascinating and will keep reading your posts to see if there are any new findings on when it’s best to spay/neuter a dog.
    I now have two Tibetan Terrier puppies that I plan to keep intact. My girl around 2 years old and my boy maybe never. That’s presently my best educated guess for giving them a long healthy life. Thanks again for sharing your knowledge on this issue with everyone!

  5. Deb on September 16, 2014 at 2:42 pm

    Hello Dr. Ettinger,
    I’m very glad I read your blog as I have an 8 month old standard male and I have been torn over whether to neuter. What do you think would be an acceptable age? Also I believe this dog also developed a vaccine induced tumor- rhabdomyosarcoma. Long story short the vet lied about where she injected the vaccine so nothing was ever reported. I went to this clinic for 15 years and felt very betrayed- I find it difficult to trust my new vet because of what happened. Any input you can give would be greatly appreciated.

  6. Lynn on October 17, 2013 at 6:17 am

    Hi Dr. Ettinger,
    I was doing research about spaying my female golden and came across your website. I was hoping to get your opinion as to spaying. My girl is now 17 months old. She had her first heat cycle when she was 14 months old (unless she had a silent heat). I was planning to spay her before her second cycle. But, the study that UC Davis published in February has terrified me. Now I feel like I fall into the “late spay” group with an even more increased risk for hemangiosarcoma. After losing three out of three goldens to cancer, two early neutered died of hemangiosarcoma just before 10), I would do anything to prevent this in my Lucy. In light of that study, and any other research you might be aware of, what do you recommend doing at this point? My options are to have her fully spayed immediately to reduce the risk of mammary cancer, not spay at all, or remove her uterus only and leave her ovaries. I am aware of the increased risk of mammary cancer if the ovaries are left, which also adds to my confusion.

    I would appreciate ANY input you might be able to provide. I realize that you do not have a crystal ball, but I am just trying to diligently question people with significant experience with Goldens and canine cancer to add to my own knowledge. I feel like this will the best way for me to be able to make the most informed decision for my girl. What would you do if she were your dog?

    Please let me know your opinion as soon as possible… THANK YOU!

  7. Jean on September 20, 2013 at 4:42 pm

    I didn’t spay my beauceron at the recommendation of my vet and she developed mammary tumors (adenocarcinomas) when she was eight years old. Three years four surgeies, two rounds of chemo, well over ten thousand dollars ad many tears (neither surgery or a top diet or supplements come cheap) we’re still fighting this. She was ALWAYS fed a top notch raw diet and supplements, no exposure to cleaning chemicas or lawn chemicals, and spring-fed water that is routinely tested. So I guess you need to pick your poision – don’t spay and deal with cancer or spay and deal with a different type of cancer….

    Me? Next time I’ll spay and place my bet on a top quality diet, low exposure to environmental carcinogens, exercise and clean water!

  8. Sabrina on July 8, 2013 at 2:59 am

    Hi Dr. Ettinger,
    This blog was very informative and I had a question I am praying you might be willing to answer. My 4yo Boston Terrier was diagnosed with Lymphoma (stage 5) in July 2012. She was treated with chemo and a Bone Marrow Transplant, doing well 6 months post-transplant. She went into heat once since transplant and seems to still be ok. However, the oncologist wants to spay her before her next heat as she fears she will come out of remission during heat as some chemo-treated dogs seem to. My question is, this breed is usually prone to MCT, and due to the carcinogens and radiation, mine is probably a higher risk for all cancers. I understand the breast cancer advantages of spaying but am concerned that the spay would put her at greater risk for many less treatable cancers. Can you offer any thoughts?

    • Dr. Susan Ettinger on August 2, 2013 at 3:30 am

      His Sabrina,
      Glad to hear that your dog is doing well post transplant (was it done at NC State?) I understand your concerns for spaying, and there are pros and cons. The preventative benefits of mammary cancer are typically when the spay is before the 2nd heat. It is not clear how long a pet needs to stay intact to have the protective effects for oth cancers. In one study they looked at spay after 1 year, so she likely has had some protective benefit from being 4. If your oncologist is concerned about the effect on her current lymphoma, that probably takes priority over the potential for other cancers, but no one knows. And also remember,intact pets get cancer too so keeping them intact in no guarantee. So no easy answer or recommendation.
      Thanks for reading, and I wish your dog a very very long remission!
      All my best, Dr Sue

  9. Lori on July 2, 2013 at 3:32 am

    So many issues to consider. I lost a Newfie to Osteosarcoma at the age of 9 and he was neutered at 6 months. It is absolutely heartbreaking to watch this horrible disease take its toll on your dear family friend. It is what bought me to you. My dog now- A pure bred St Bernard, I had originally planned to neuter between 6 and 8 months, got postponed because he suffered bloat at 4 months(a whole other huge topic I had to learn a lot about in a short time and realizing that I probably had the youngest dog to ever suffer bloat because there is absolutely nothing available as far as care plans and recovery and feeding plans for young dogs with tendency to bloat, the emergency vet said she had never done bloat surgery on a dog that still had his puppy teeth) , the surgery and recovery slowed his growth and our vet suggested we wait a until he had finished growing stating that early neutering can affect head size and bone growth in St.s. Then when he turned a year and a half we had a blood work up on him prior to scheduling his neutering and he showed elevated creatine (sorry if I spelled wrong) and abnormal kidney levels and elevated protein levels and there was consern about his adrenals sorry I may have the details wrong here I don’t have it in front of me but the vet said that possibly a raw diet could contribute to the protein levels and kidney levels. he is not on a raw diet but after nearly losing him to bloat he is on a grain free diet – (Orijens and tiki dog at the time) which tends to have higher protein than other dog foods, she said to change his food and re test , he now eats Blue Buffalo grain free large breed. So we will see about that…meanwhile my daughters black lab went into heat and I learned what its like to have a very aroused st bernard around the house ( please everyone save the comments about having two intact dogs in my house, I am fully aware of how irresponsible my daughter is, and I am for that matter, for allowing her dog to remain intact, another reason why we should never believe our kids even when they are 18 that they will take care and be financially responsible for the dog they MUST have.) We kept them separated and I do not believe any litter will result (it has not been 63 days yet fingers and toes crossed) Excuse my meanderings here, but getting down to it, I am wondering if I should neuter my male St. at all, given the high occurrence of osteosarcoma and other cancers in large breeds as well as dementia and other brain ailments. With the possibility of the looming kidney disease that his blood work pointed toward I have lots to think about.-Side note he (my dog) does not seem sick or have any visible health problems, he east well, drinks well, eliminates well etc. Knowing now what I did not then he is on a much higher quality diet and gets supplements of salmon oil daily. I was quite ignorant raising my Newfie and did not realize the correlation of crappy food to health -nor did I for myself for that matter at that time.
    Thank you for putting issues however passionate each side may be out there and for shedding light on unpopular choices and for translating all of the scientific research findings in to real language for the non scientists out her. I always look forward to your blog posts.

  10. Petchiro on June 20, 2013 at 5:05 pm

    While i realize that in some areas an over abundance of animals is a real issue, BUT i am continuosly hearing of many shelters in many areas of the country being so short of adoptable pets that THEY ARE IMPORTING FROM OTHER COUNTRIES!!!!! So while i agree that most people should NOT own an intact animal of any kind (and quite frankly most of them should be spayed and neutered themselves to prevent unwanted humans from being brought into this world), spaying and neutering should not be shoved down the throats of every pet owner in the Country. And being a responsible owner myself (I train and show ALL of my dogs) I am getting sick and tired of the animal “rights” groups and individuals constantly trying to force spay/neuter on everyone including trying to create mandatory spay/neuter laws in many States (including mine!). I won’t force you to keep you pet intact, don’t try to force me into spaying or neutering mine. I am so glad that all of this new research is finally coming to light and the brave and forward thinking vets like Dr. Sue are willing to step forward with it (many of us in the dog world have been aware of some of the research for quite some time now). If you wouldn’t remove the ovaries and testicles in a young child due to the adverse affects it would have on their development and health, why in the world would you think it would be ANY different for an animal? Common sense people…even without the research!

    • Dr. Susan Ettinger on June 26, 2013 at 3:49 pm

      Thanks Petchiro! I appreciate the support!
      All my best, Dr Sue

  11. Pam Wilkinson on June 15, 2013 at 9:29 pm

    Yeah Sarah! I will continue to spay and neuter too no matter what, until the pet over population is 90 percent better in America. It is so devastating to know 14,000 dogs and cats are killed every single day and each dog/cat is as wonderful as mine, I know. I am a responsible person and would never allow pups or kittens to be born yet I do know accidents happen so I spay/neuter right away. I also have older pets get cancer and this is how I found this wonderful resource that has helped incredibly so to keep them comfortable with diet and vitamins for years past any onocologist could imagine. I personally have cancer and the lessons I have learned from my wonderful animals has also prolonged my life just by diet alone. It’s amazing. By the way, I’m not sterilized.
    Thank you too Dr. Sue for your comment. Yet I really feel lawn fertilizer and diet is more of a culprit for pets to get cancer. Or maybe it’s just age. I do love your diet suggestions that have prolonged comfort and life.

    • Dr. Susan Ettinger on June 18, 2013 at 3:31 pm

      Thanks Pam. Wishing you and your pets continued good health!
      Dr Sue

  12. Donna on June 15, 2013 at 1:59 am

    sorry – one more thing – I have my dog on keegan water – High ph

  13. Donna on June 15, 2013 at 1:37 am

    I have a golden that has had 3 DIFFERENT cancers in the past 2 years – he has had 3 surgeries 4 months of chemo – I presently have him on the “cancer diet” – it is a praying game I suppose – he was neutered at 10 months of age – I did not have him microchipped (did not want any foreign body in him given risk of golden cancer) I went to great lengths to research breeders – his mom is from usa and dad from europe ( hoped that would eliminate over breeding – his dad had only arrived 1 month earlier and mine was from first litter) this has been a real heartbreak for us bc he seems to be a tumor factory – just recently heard that chemical neuter can be done and it maintains a small amount of testosterone in dog – not sure if that changes anything for future dogs – havent had chance to really look in to it…..

  14. Sarah on June 14, 2013 at 2:09 pm

    One problem of letting people adopt an intact dog with the “promise” of getting it altered at a later time is that many people postpone & procrastinate, and then oopsie, unwanted pregnancy. The surplus of dogs in this country is staggering, yet most people don’t make the connection between having their fluffy bred “just once” or their lack of attentiveness at protecting against pregnancies and the reality of vast numbers of dogs & cats euthanized every day in this country. The discussion of pros & cons of altering an animals is interesting & important, but to me it is premature until the overpopulation issue is resolved. And I say this as a dog-mom who lost a goldendoodle to hemangiosarcoma, so I know how tempting it sounds to NOT neuter in order to gain some protection against cancer. If I can do something to reduce the need for euthanasia – like supporting spay/neuter – then that’s what I want to do.

    • Dr. Susan Ettinger on June 18, 2013 at 3:22 pm

      I agree we have a lot to learn about the association of spay/neuter and cancer. And as you point out the pet overpopulation issue is real and serious. I am just sharing the new info, because we must all make educated decisions for ourselves. While pet overpopulation is staggering, as you also know, having a pet go through cancer is devastating as well. Will keeping your pet intact prevent cancer? No but there is a role. I just want us to have a respectful discussion. Thanks for joining in! I am so sorry about your dog and your loss.
      All my best, Dr Sue

  15. Ann M. McHugh on June 13, 2013 at 1:21 pm

    A whole lot more food for thought. I really think the age of the altered animal is significant -the closing of the bone growth plates at the time determined by genetics vs the artificial late closing due to the removal of sex hormones.is significant.
    BTW I DO RESCUE – I transport, pull, and overnight all kinds of rescues, but mostly Keeshonden and Eskies. Fortunately there are very few Kees in shelters and if we find them we pull them, foster and rehome them. Eskies being smaller are more common in shelters. I have a foster failure rescue eskie from after Hurricane Katrina and I have two Kees that came to live with me when their breeders/owners died. I had the eskie spayed, but not as soon as I got her- I waited till she had adjusted to our home, and her immune system had time to recover from all the vaccines the shelter in Georgia pumped into her. She was approx. 2 yrs old at the time of spaying. The attitude of some shelters and rescuers that all puppies MUST be altered when they are adopted is detrimental in my opinion. Esp if the puppies are 8 weeks old!! because I have never heard of a pregnant 10 week old bitch or heard of a dog fathering a litter at that age. If you feel it is a good home – this is esp for private shelters- you have to believe that the new family will be responsible when dealing with intact dogs and bitches or you shouldn’t adopt to that family/person.

  16. Brandy Morris on June 13, 2013 at 3:09 am

    I have a 7 year old male Flat Coat Retriever and he was diagnosed with Lymphoma at the age of 5. My pup’s oncologist told us at the time that there was a large increase of dogs with lymphoma at younger ages. He said it was likely due to neutering under the age of 6 months and the lack of developmental male hormones. These hormones effect digestion and immune support. We had to change to a specific immune support diet that would regulate his hormones and balance his body. This should be part of a discussion before having your furbaby fixed.

    • Dr. Susan Ettinger on June 13, 2013 at 4:46 pm

      I agree, Brandy! I am sorry about the lymphoma in your dog.
      All my best, Dr Sue

  17. Amy on June 12, 2013 at 10:55 pm

    Even experienced breeders sometimes have unwanted litters. If you want to have just one dog and are willing to put up with the mess and behavior of “heat,” and you have a good fence… okay maybe. But if you want to have more than one dog that complicates things. My young cocker humped my geriatric cockers when she was in heat, and she was also protective of her toys. Now that she’s been spayed there are no more behavioral problems.

    You didn’t mention this, but I would want to know if those studies controlled for age. If neutered/spayed dogs live longer, wouldn’t cancer happen due to the age anyway?

    • Dr. Susan Ettinger on June 13, 2013 at 4:44 pm

      Good point about is living longer the reason neutered dogs got cancer? I think there are more factors involved. Not all cancers were increased in neutered dogs (no effect on SCC and melanoma)
      Yes there are behavioral issues too with intact vs neuterd. Interestingly, another recent study found that neutering increased aggression problems in female dogs. In addition there are dementia issues I did not discuss. (Castrated elderly male dogs are greater risk for canine dementia). It is complex!
      All my best, Dr Sue

  18. Spay/Neuter and Cancer in Dogs | Dog FYI: Dog Health Information Library on June 12, 2013 at 6:00 pm

    […] Spay/neuter and the association with cancer in dogs: part one Spay/neuter and the association with cancer in dogs: part two Spay/neuter and the association with cancer in dogs: part three […]

  19. Christine on June 12, 2013 at 4:41 pm

    Thank you for addressing this issue. You’re right, there is no discussion with vets when it comes to neutering a dog. They just assume you are going to do it and really push for it. There’s zero discussion of pros and cons. I understand the huge overpopulation issue we have here in the US, but I still feel that owners deserve to make an informed decision. Especially if they have a breed that has a high rate of some of these aggressive cancers. Two of my dogs died of cancer during the past two years – osteosarcoma and hemangiosarcoma. It’s a terrible disease.

    • Dr. Susan Ettinger on June 13, 2013 at 4:35 pm

      Well said about making an informed decision! And I am so sorry for all the loss you have suffered!
      With sympathy, Dr Sue

  20. michele on June 12, 2013 at 3:45 pm

    hi…. do you think hear tworm pills are a good idea or are they causing more harm than good in the long run.

  21. Mary on June 12, 2013 at 12:49 pm

    Well, I really appreciate this series, because it is laying out the pros and cons for us to decide. If Europeans are more responsible than we are when it comes to caring for their animals — and I agree they are — it’s likely because they are educated about what it really means to take care of an animal, and they get the chance to think about it ahead of time. I’m really glad to Dr. Ettinger is taking the time to educate us about this subject so we can BE more responsible, intelligent, and proactive from now on. I don’t think we fix the problem of lazy ownership by just fixing all the dogs.

    • Dr. Susan Ettinger on June 13, 2013 at 4:34 pm

      Thanks Mary for reading and joining the discussion!
      All my best, Dr Sue

  22. Pam Wilkinson on June 12, 2013 at 11:21 am

    Thank you for mentioning dogs and cats live longer when sterilized. Most animals hit by cars are intact because they have the urge to get out and roam. Males can smell a female in heat up to 6 miles. They do not look both ways before crossing the street.
    Europeans are more responsible and intelligent than Americans. There is not a pet overpopulation problem in Europe. Here in the U.S. at least 14,000 dogs and cats are euthanized everyday simply because they were born unwanted. You mention the biggest killer of dogs is cancer, I beg to differ, it’s euthanasia of the unwanted disposable pet (here in America). Also People get cancer and they didn’t get sterilized. Cancer is something in our society. I wish spay/neuter was as rampant as cancer. This would certainly repair the gruesome pet overpopulation of 14,000 dogs and cats being killed at shelters every day, day in and day out, for decades, (here in America). Your article is certainly not going to help reduce the disgusting kill rate for the unwanted pets being born. Also you may wish to fix the areas in your article from neuter a female to spay a female.

    • Dr. Susan Ettinger on June 13, 2013 at 4:33 pm

      Again thanks for your comments. As I said, I am not against spay and neutering. While the pet overpopulation is an IMPORTANT issue, there is important info coming out about sex hormones and cancer. For responsible pet owners with high risk cancer breeds, I think this is an important discussion. Cancer in pets is an epidemic!! It is estimated that 50% of dogs over the age of 10 get cancer. It is devastating to the family and very costly to treat. It is time to have a discussion.
      As for neuter, it technically refers to the removal of reproductive organs of either sex, though it is more commonly the term for males. Still it is not incorrect to use neuter for females.
      Dr Sue

  23. Nancy on June 12, 2013 at 11:09 am

    Was diet taken into consideration for any of the studies?

    • Dr. Susan Ettinger on June 13, 2013 at 4:25 pm

      Great question, but no I did not see diet in the studies.
      Dr Sue

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